1. Field of the Invention
The present invention relates to a polarization converter which produces polarized light having an identical polarization direction, and to a lighting device for an LCD panel using the polarization converter.
2. Description of the Related Art
In a liquid crystal display in which a liquid crystal display element (LCD panel) must be illuminated with polarized light having an identical polarization direction (linearly polarized light), various kinds of polarization converters are used. In particular, an LCD panel for a notebook personal computer, a digital camera or a video camera is illuminated using a thin lighting device (backlight). In general, in a known backlight in which unpolarized light from a light source is transmitted through a wedge-shaped light guide element and is emitted outside from one surface thereof, a polarization converter is provided between the emission surface of the light guide element and the LCD panel. The polarization converter absorbs 100% of light of a specific polarization direction (oscillation direction) from unpolarized light, the oscillation direction thereof being random, and permits a polarized light component whose polarization direction is perpendicular to the specific polarization direction to pass therethrough. Therefore, there is an inevitable light energy loss of at least 50%.